Journal of Veterinary and Animal Sciences

Abstract

Infectious canine hepatitis caused by Canine Adenovirus type 1 (CAV-1) is a systemic disease of domestic and wild canids. Despite the availability of effective vaccines, sporadic infections continue to occur, while information on the molecular epidemiology of CAV-1 in Kerala remains limited. The present study investigated the occurrence and molecular characteristics of canine adenoviruses in dogs from Wayanad and Kozhikode districts of northern Kerala. A total of 45 samples, comprising rectal swabs from 21 dogs with haemorrhagic enteritis, 18 apparently healthy dogs, and tissue samples from six fatal cases, were screened by PCR targeting the E3 genomic region. Thirteen samples (28.9%) were positive for CAV-1, including one from an apparently healthy dog, while two post-mortem samples were positive for CAV-2. Affected dogs exhibited haemorrhagic diarrhoea, vomiting, anorexia, lethargy and icterus, with multisystemic lesions observed in fatal cases. Two representative CAV-1 amplicons were subjected to Sanger sequencing and phylogenetic analysis. The sequences exhibited 99.12 per cent reciprocal nucleotide identity and high similarity with Indian and international CAV-1 strains. Amino acid analysis revealed Trp126Ser and Thr184Met substitutions in one isolate, whereas these substitutions were absent in the other. Phylogenetic analysis based on the partial E3 gene and flanking regions confirmed both isolates as CAV-1 and demonstrated their association with different groups of Indian strains, suggesting the circulation of genetically distinct CAV-1 variants in the region. The findings confirm the continued circulation of CAV-1 in northern Kerala and highlight its potential association with haemorrhagic enteritis and systemic disease in inadequately immunised dogs.